Reduction of risk for growers : methods for the development of disease-resistant crops

Summary Systemic acquired resistance (SAR) appears to be a ubiquitous higher plant defence response. Resistance is dependent on the high-level expression of SAR genes. Mutations, transgenes or chemicals that cause high-level SAR gene expression also cause resistance to pathogens. Furthermore, when SAR is eliminated, through the reduction of salicylic acid accumulation or activity, generalized severe disease-susceptibility occurs. Therefore, SAR appears to be an essential component of the defensive repertoire that ensures plant health in nature. Chemicals that activate SAR in the field, as well as crop varieties with constitutive SAR gene expression, will provide new solutions to disease problems for growers in the near future.